Science Buddies: "Ask an Expert"

My son competed in a small science fair and one of the comments the judge made was that he should have used p values.
My son is now going on to a larger fair and he wants to include them. I’m trying to learn about p values so I can help him understand them.
My son asked the questions “Will changing the model rocket engine change the speed, maximum altitude, and parachute deployment of the model rocket?”

He used 4 different types of model rocket engines. Would a p value be calculated for the difference between each engine for speed, maximum altitude and parachute deployment? Would he compare the results between engine 1 to engine 2, 3 and 4? Or would he compare engine 1 to 2 and 2 to 3 and 3 to 4?

We found an online calculator and he was putting in the data and getting the results, but I wasn’t sure how to advise him on which data to compare.

Thank you far your help.
Hope

Hi HopePressler1,

Congratulations to your son for moving on to the larger science fair!

Your son might use t-tests for comparing the rocket engine results. A t-test can be used to estimate the probability (p value) that two mean values are different. A series of t-test calculations could be made to compare all possible pairs of your rocket engines. That is engine 1 compared with engines 2, 3 and 4; engine 2 compared with engines 3 and 4; and engine 3 compared with engine 4. And you'd need to complete the series of t-test calculations for each of the independent variables mentioned in your post.

I hope this helps. Please ask again if you have more questions.

A. Norman